Alternating-current wattmeter.



No. 642,164. Patented Jan. 30. I900.

K. n. F. SCHRUTTKE'. MLTERNATlNG CURRENT WATTMETER.

(Application filed. Apr 22. 1899.)

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No. MW. Patented Ian. 30, I900. K. 0. F. SCHROTTKE.

AL TE RNATING CURRENT WATTWIETER.

(Application filed Apr. 22, 1899,

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UNTTEn STATES PATENT OEEICE.

KARL OTTO FRANZ SCIIROTTKE, OF BERLIN, GERMANY, ASSIGNOR TO THE SIEMENSdz IIALSKE ELECTRIC COMPANY OF AMERICA, OF CHICAGO,

ILLINOIS.

ALTERNATlNG- CURRENT WATTlVl ETER.

SPECIFICATION forming part of Letters Patent No. 642,164, dated January30, 1900.

Application filed April 22, 1899.

To all 2071 0127, it may concern.-

Be it known that I, KARL OTTO FRANZ SCHROTTKE, a subject of the Emperorof Ger many, residing at Berlin, Germany, have invented a certain newand useful Improve ment in Alternating- Current \Vattmeters, (Case No.186,) of which the following is a full, clear, concise, and exactdescription.

My invention relates primarily to alternat- 1O ingcurrent wattmeters,and has for its object the provision of improved means for ad j ustingdifferences in phase in the energizingcircuits of the meter.

The invention is primarily adapted for use in connection with thosecircuits conveying heavy currents or currents of high electromotiveforce in the measurement of which great difficulty has been found in thepast owing to the inadequate means heretofore 2o employed.

ivhile my invention is primarily adapted for use in connection withalternating-current meters, I do not wish to be limited in itsapplication, as it may be employed in connection with other motivedevices.

My invention will be more particularly described by reference to theaccompanying drawings and will be pointed out in the claims.

In the drawings, Figure 1 is a sectional view of a transformer which maybe employed in practicing my invention. Fig. 2 is a diagram indicatingthe circuit connections of an ampere indicator or meter. Fig. 3 isadiagram illustrating the phase relations of the currents in thecircuits illustrated in Fig. 2. Fig. at is a diagrammatic viewindicating a watt meter or indicator, together with the circuitconnections, arranged in accordance with my invention. Fig. -5 is adiagrammatic View illustrating the phase relations of the currents inthe circuits shown in Fig. 4. Fig. 6 is a diagrammatic View indicatingapparatus equivalent to that shown in Fig. I, the circuits beingsomewhat modified. Fig. 7 is a diagrammatic view indicating the eirc uitconnections of a pressure or volt meter or indicator. Fig. 8 is adiagrammatic view indicating the phase relations of the currents shownin Fig. 7. Fig. 9 is a diagrammatic view indicating another type ofalternating current watt motor or recorder constructed in accordanceSerial No. 714,044. (No model.)

with my invention. Fig. 10 is a diagrammatic view indicating the phaserelations in the currents shown in Fig. 9. Fig. 11 inclicates,diagrammatically, a third embodiment of my invention. Fig. 12 shows,diagrammatically, the phase relations between the currents in thecircuits indicated in Fig. 11. Fig. 13 illustrates a fourth embodimentof my invention. Fig. 14 diagrammaticallyin- 6o dicates the phaserelations between the cur rents in the different circuits shown in Fig.13.

Like letters indicate like parts throughout figures illustrating similarapparatus.

In Fig. 1 I have shown a transformer constructed in a well-known way,this transformer being adapted for use in measuring the amperage ofalternating current,one winding of the transformer being of largecrosssection and constituting the series winding, the secondary winding5 being preferably surrounded by the primary winding, a suitablemagnetic core a being provided.

In Fig. 2 is diagrammatically illustrated the transformer shown in Fig.1, an ampere or current indicator Abeing included in circuit with thesecondary coil, the arrangement be ing such that the current may readilybe measured by passing only a very small proportion of the currentthrough the delicate measuring instrument.

The apparatus illustrated in Fig. 2 is of course adapted only toindicate the volume of current flowing in the consumption-circuit, whichincludes the primary coilp.

In accordance with my invention transformers are employed whose primarycoils may either be in series with the consumption-circuit, as shown inFig. 4, or the primary coil may be in a bridge of the conductors of theconsumption-circuit, as shown, for example, in Fig.9, or two separatetransformers may be employed, one having its primary coil in series withthe conductors of the consumption-circuit and the other with its primarycoil in a bridge of the conductors of the consumption-circuit, as shown,for example, in Fig.13.

I will first describe the preferred embodiments of my inventionemploying transformers Whose primary coils are connected in se- I00 rieswith the mains of the consumption-circuit in order that the inventionmay thoroughly be understood and will then briefly describe thoseembodiments of my invention in which transformers are employed whoseprimary coils are in bridges of the main conductors of theconsumption-circuits.

In order to constitute a wattmeter, the instrument has, as is wellknown, one energizing-circuit in series with the main conductors andanotherenergizing-circuit in a bridge of the main conductors; but thisarrangement simply will not be sufficient accurately to measure the workfor the reason to be presently pointed out. Referring to Figs. 2 and 3,the current J in the secondary circuit may have such a shift of phase,as is indicated in Fig. 3, from the electromotive force in the secondarycircuit. It may be considered that the primary current J is resolvedinto two components-the magnetizing-current J serving to create thetransformer-field M and a component J in opposition to the secondarycurrent J flowing through the measuring, instrument A. The current J isdisplaced from the primary current by an angle a and lags behind itspressure E by an angle (p. The

ratio J :J to be sure, does not absolutely correspond to the translatingratio of the transformer; but it will practically remain constant if theair-gap Z in the transformer is large, so that it will merely benecessary to multiply the indications of the instrument Abya constant inorder to ascertain the amperage of the primary current J that is beingused.

NVhile the apparatus shown in Fig. 2 is adapted to the measurement ofthe volume of current, it is not adapted to the measurement ofelectrical work by the mere addition of a bridge-coil tothe indicator,because the current J flowing through the measuring instrument A has ashift of phase with relation to the primary current J such, for example,as is indicated in Fig. 3, which by not being taken into considerationwould result in erroneous measurements.

I11 order to operate the meter accurately, I provide means for shiftingthe secondary current J exactly one hundred and eighty degrees. To thisend I may adopt the arrangement diagrammatically indicated in Fig. 4, inwhich an energizing-circuit in a bridge of the main conductors is addedto the measuring instrument A. In order to shift the phase of thesecondary current J I provide an active resistance, which is preferablyan ohmic and non-inductive resistance r, in parallel with the secondarycoil of the transformer and the coil y of the instrument in circuit withthe secondary coil. By means of the active resistance the current Jbecomes the resultant of the current J in the resistance r and thecurrent J in the coil of the meter in circuit with the secondary coil ofthe transformer, the latter current by the proper adjustment of theresistance r being shifted one hundred and eighty degrees in phase fromthe primary current J By this means the indications of the watt meterorindicator become independent of the shift in phase in the currenttransformer. In general the shift of phase produced by theself-induction of that coil of the watt meter or indicator in circuitwith the secondary coil of the transformer is sufficiently large. Ifnot, it may be brought to the desired degree of self-induc tion byswitching into circuit therewith conductors of sufficientself-induction.

In Fig. 5 is shown the effect of the additional resistance r upon thecurrent in the instrument. The secondary current J now consists of twocomponents-the currentJ in the non-inductive resistance r and thecurrent J in the instrument. The current J is shown as displaced exactlyone hundred and eighty degrees from the primary pressure J The current Jis in phase with its pressure 6 In Fig. 6 I have shown an apparatusequivalent to that shown in Fig. 4, the active non inductive resistance0' being included in a circuit inductively related to the coil of thetransformer in circuit with an energizing-coil of the indicator, thephase of the current in the latter coil being suitably adjusted by theresistance r. A

I will nowbriefiy describe the embodiment of my invention employingtransformers Whose primary coil is of high resistance and connected in abridge between the main conductors of the consumption-circuit.

An apparatus for measuring the potential difference in the mains isdiagrammatically indicated in Fig. 7, the phase relations beingdiagrammaticallyindicated in Fig. 8. The apparatus shown in Fig. 7 isadapted to measure the voltage of high-pressure currents, the voltage ofthe current 71 in the secondarycircuit being sufficiently reduced toprevent bodily injury to the operator.

In Fig. 8 the primary current 1 may again be considered divided into twocomponents, the magnetizing component creating the field IIO M and acomponent opposite to the secondary current 4' The secondary pressure 6lags behind the primary pressure D by an angle [3, the current i beingin phase with the magnetizing component 1; of the pressure. As will beclear from this figure, the current 2' in the secondary circuit of thetransformer, which circuit includes the energizing-coil of theindicator, has a difference of phase from the electromotive force D ofthe primary circuit, and although this difierence in phase has butlittle appreciable effect in the measurement of electromotive forces itspresence would render the measurement of the energy consumed in theprimary circuit faulty.

In adapting the transformers connected, as shown in Fig. 7, to themeasurement of energy I may adopt the arrangement shown in either Fig. 9or Fig. 11. In the apparatus shown in Figs. 9 and 11 I have included oneenergizing-coil y of each indicator in series with In Fig. 9 I have conamain conductor.

nected a coil 8,, having suitable self-induction, in parallel with theenergizing-coil of the meter in series with the main conductor. Byproper adjustment of the coil S the current J in the said series coil ofthe indicator may be shifted in phase so that it may differin phase fromthe shunt-current by exactly one hundred and eighty degrees, asindicated in Fig. 10, assuming that the main current J has no differencein phase with relation to the electromotive force D of the main orprimary current, so that in this case also the energy may be measuredindependently of the phase differences in the transformer.

Fig. 10 is an amplification of Fig. 8. The main current J is shown inthis figure as in phase with its pressure 1) and divided into twocomponents, the component J, flowing in the coil S and the component Jflowing through the coils of the instrument. The currents J and 1 areshown one hundred and eighty degrees apart.

In Fig. 11 instead of modifying the current flowing through the seriesenergizingcoil y of the indicator I modify the current flowing throughthe sh unt-coil or that coil in circuit with the secondary coil of thetransformer. An active inductionless resistance r is included inparallel with the secondary coil of the transformer and the energizingcoil ,2 of the indicator, by which resistance the current i may beshifted one hundred and eighty degrees in phase from the electromotiveforce D in the primary circuit, as is indicated, diagrammatically, inFig. 12. In some instances also I have employed an induction-coil S moreaccurately to adjust the apparatus.

In Fig. 12 the primary current 2', consists of two components-thecurrent i creating the field M, and a component in opposition to thesecondary current 2' The primary pressure D has two components-thepressure 7; in phase with the current i, and a component in oppositionto the secondary pressure e The secondary current 2 is divided into twocomponents-the component 1', in the non-inductive resistance 7' and thecomponent 2', flowing through the coils of the instrument. Theresistance 1) may be so chosen that the component t} will be displacedone hundred and eighty degrees from the pressure D, as is clearlyillustrated in the figure.

In Fig. 13 I have employed two transform ers, the primary of one beingincluded in series with the main circuit and the primary of the other ina bridge of the main circuit. Each secondary coil of the transformer isincluded in series with an energizing-coil of the indicator. Thesecondary coil of the trans former T, is included in series with theenergizing'coil g and the secondary of the trans former T,. is connectedin circuit with the energizing-circuit A non-inductive resistance r,suitably adjusted, is connected in parallel with the secondary of thetransformer T and the energizing'coil 1 By the proper adjustment of theresistance r the required phase adjustment in the indicator may besecured, as diagrammatically indicated in Fig. 14. In this figure theimpressed pressure D has two com ponents-the magnetizing component t anda component in opposition to the secondary pressure c,. The primarycurrent J in the transformer T has also two componentsthe magnetizingcomponent J creating the field M anda component in 0pposition to thesecondary current J primary current i, of the transformer T has two componentsthe magnetizing component i creating the field M and aeomponentin opposition to the secondary current i The current J isdivided into two components-- the component J in the resistance 1' andthe component J in the coils of the instrument. The pressure E acrossthe resistance r is in phase with the current J The currents J and i,must be in phase, as is shown in the figure.

Having thus described my invention, I claim as new and desire to secureby Letters Patent-- 1. The combination with a transformer having awinding in circuit with main conductors, of a secondary windingtherefor, a wattmeter having one winding out of circuit with the mainconductors and in circuit with the secondary of the transformer, asecond winding receiving its current independently of the saidtransformer, and a phase-modifier to restore the proper phase relationbetween the currents in the coils of the meter that would otherwise bedestroyed by the transformer, substantially as described.

2. The combination with a transformer having a winding in circuit withmain conductors, of a secondary winding therefor, a wattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding receiving its currentindependently of the said transformer, and a phasemodifier in parallelwith one of the windings of the meter to restore the proper phaserelation between the currents in the coils of the meter that wouldotherwise be destroyed by the transformer, substantially as described.

3. The combination with a transformer having a windingin circuit withmain conductors, of a secondary winding therefor, a wattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding receiving its currentindependently of the said transformer, and a phase-modifier in parallelwith the secondary coil of the transformer and the coil of the meterconnected therewith to restore the proper phase relation between thecurrents in the coils of the meter that would otherwise be destroyed bythe transformer, substantially as described.

at. The combination with a transformer hay-- The inga windingin circuitwith main conductors,

, of a secondary winding therefor, a wattmeter having one winding out ofcircuit with the main conductors and in circuit with the secondary ofthe transformer, a second winding receiving its current independently ofthe said transformer, and a phase-modifier associated with the secondarycircuit, to restore the proper phase relation between the currents inthe coils of the meter that would otherwise be destroyed by thetransformer, substantially as described.

5. The combination with a transformer having a windingin circuit withmain conductors, of a secondarywinding therefor, awattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding receiving its currentindependently of the said transformer, and a resistance in parallel withone of the windings of the meter to restore the proper phase relationbetween the currents in the coils of the meter that would otherwise bedestroyed by the transformer, substantially as described.

6. The combination with a transformer havinga winding in circuit withmain conductors, of a secondary winding therefor, a wattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding receiving its currentindependently of the said transformer, and a resistance in parallel withthe secondary coil of'the transformer and the coil of the meterconnected therewith to restore the proper phase relation between thecurrents in the coils of the meter that would otherwise be destroyed bythe transformer, substantially as described.

7. The combination with a transformer having a winding in circuit withmain conductors, of a secondary winding therefor, a wattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding receiving its currentindependently of the said transformer, and a resistance associated withthe secondary circuit, to restore the proper phase relation between thecurrents in the coils of the meter that would otherwise be destroyed bythe transformer, substan tially as described.

8. The combination with atransformerhaving a winding in a bridge of mainconductors, of a secondary winding therefor, a wattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding in series with a mainconductor, and a phase-modifier connected in parallel with one of themeter-windings to restore the proper phase relation between the currentsin the coils of the meter that would otherwise be destroyed by thetransformer, substantially as described.

9. The combination with atransformerhaving a winding in a bridge of mainconductors, of a secondary winding therefor, a wattmeter having onewinding out of circuit with the main conductors and in circuit with thesecondary of the transformer, a second winding in series with a mainconductor, and a resistance included in parallel with the secondary coilof the transformer and the winding of the meter connected therewith, torestore the proper phase relation between the currents in the coils ofthe meter that would otherwise be destroyed by the transformer,substantially as described.

10. The combination with the main conductors of analternating-current-supply circuit, of a transformer having a winding ina bridge of the main conductors of the circuit, a secondary for thetransformer, a wattmeter having one winding out of circuit with the mainconductors and in circuit with the 'secondary of the transformer, asecond winding of the meter receiving its current independently of thetransformer, and a phase-modifier for restoring the proper phaserelation between the currents in the coils of the meter that wouldotherwise be destroyed by the transformer, substantially as described.

In witness whereof I hereunto subscribe my name this 28th day of March,A. D. 1899.

KARL OTTO FRANZ SCHROTTKE.

WVitnesses WOLDEMAR HAUPT, HENRY HA SPER.

